Most of the word/coarse level cells have an assigned group and individual page.
The gate/fine level cells are all on one page.
Fix links to `cell_library.rst`.
New `help -dump-cells-json <file>` to dump cells list.
Add 'group' field to SimHelper class/struct with defaults to gate_other and word_other depending on source (simcells or simlib).
Add 'unary' group to unary operator cells for testing (based on internal cell library docs page).
- Drop `cell_code` and instead map code lookups to the `cell_help` dict.
- Add helper functions to struct for checking and getting the right cell.
- Add `CellType` for cell to `write_cell_rst` function declaration in
preparation for use in future.
- Iterate over `yosys_celltypes.cell_types` when exporting cell rst files,
reporting errors for any cells defined in `cell_types` but not
`cell_help_messages`.
Since `simcells.v` uses consistent formatting we can handle it specifically to help tidy up sphinx warnings about the truth tables, and instead chuck them in a code block which when printing to rst.
Also has the side effect that rst code blocks can be added manually with `//- ::` followed by a blank line.
Include Source file and line number in SimHelper struct, and use it for verilog code caption in rst dump.
Also reformat python string conversion to iterate over a list of fields instead of repeating code for each.
Allows for more expressive code when constructing help messages for cells.
Will also move extra logic in parsing help strings into the initial python parse instead of doing it in the C++ at export time.
The default mapping rules for division-like operations (div/divfloor/
mod/modfloor) invoke subtractions which can get mapped to carry chains
in FPGA flows. Optimizations across carry chains are weak, so in
practice this ends up too costly compared to implementing the division
purely in soft logic.
For this reason arrange for `techmap.v` ignoring division operations
under `-D NODIV`, and use this mode in `synth_quicklogic` to avoid carry
chains for divisions.
The new bitwise case equality (`$bweqx`) and bitwise mux (`$bwmux`)
cells enable compact encoding and decoding of 3-valued logic signals
using multiple 2-valued signals.
iverilog complains about implicitly truncating LUT when connecting it to
the `$bmux` A input. This explicitly truncates it to avoid that warning
without changing the behaviour otherwise.
